Booster pump screen



DeCe 22, 1942. I R, R CUR-|15 2,3065297 Y BoosTR PUMP SCREEN Filed Aug.. 14, 1941 II:I

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IILII IGI Patented Dec. 22, 1942 UNITED `STATES PATENT o Erica BOOSTER SCREEN -Russell Curtis, Dayton, 0hio, assignor to Curtis Pump Company, Dayton, Ohio, a corpora-,-

tion of Ohio Application August 14,' 1941, Serial No. 406,742

14 Claims.

'I'he present invention relates to high altitude fuel systems for aircraft and more particularly to filtering means therein for straining fuel before it is delivered to an engine.

The lter assembly herein illustrated and described is preferably, although not necessarily,

adapted for use with a booster pump of the type disclosed in my copending application entitled Booster pump for aircraft fuel systems," Serial No. 352,064, filed August 10, 1940.

In the specification of my copending application it is proposed to employ a booster pump in y such an arrangement with respect to the fuel tank that fully liquid fuel may be fed from -a vented tank source considerably above the altitude in which there is a separation of air, other fixed gases, or vapors from the liquid fuel therein. By using a centrifugal booster pump having a flared throat, the fuel is subjected to a Whirl-I pool action as it leaves the fuel tank, whereby the lighter gaseous bubbles are thrown upwardly and outwardly into the tank while fully liquefied fuel is delivered under pressure to the delivery line of the fuel system.

It is important that the fuel thus delivered be free of any foreign matter which might be injected into the fuel tank when the latter is filled. Preferably, the fuel should be strained as it leaves the fuel tank and enters the booster pump.

However, any iilter assembly provided must necessarily be so arranged as to satisfactorilystrain all of the fuel entering the booster pump without interfering with the separation of the gaseous bubbles from the fuel and withoutl restricting their path of flow outwardly and upwardly from the booster pump throat through the fuel in the fuel tank.

It is, therefore, an important object of this invention to provide means for filtering liquid fuel in a fuel system at a point which does not interfere with the delivery of the fuel to an engine.

Another object of the present invention is to provide a. filter assembly at the outlet of a fuel tank which will strain the fuel flowing therethrough without restricting the upward and outward flow of gaseous bubbles separated from the liquid fuel in the tank outlet.

A still further object of the present invention is to provide a screen assembly for the outlet of a fuel tank which guides the ow of fully liquid fuel to the pump while deflecting the flow of gaseous bubbles away from the incoming liquid fuel.

A still further object vof the present invention is to provide a screen assembly at the outlet of a fuel tank positioned over the 4inlet to a cen-'1 trifu'gal booster pump in whichva deflector member in the screen assembly directs the flow of fully liquid fuel into the pump along an axial path of the assembly and deflects the'flow of gaseous bubbles separated from the fuel along an outward path back through the screen.

.Still another object of the present invention is to provide'a screen assembly in combination with the'fiared throatof a centrifugal booster pump at' the outlet of a fuel tank for deilecting gaseous bubbles rising fromrthe throat back through theA screen at, relatively high velocities. y

The lnovel features believed to be characteristic ofthe present inventionareset forth with par.V

ticularity in the appended claims. `The invention itself, however, both as to its organization and manner of construction, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in which:

Figure 1 is a broken view ln vertical cross section, with parts in elevation, of a filter assembly in a fuel system constructed and arranged in accordance with the principles of the present invention;

Figure 2 is a fragmentary top plan view in elevation of the screen assembly as seen substantially in the plane indicated by the line II-II and looking in the-direction of the arrows;

Figure 3 is a view similar to Figure 2,'il1us.

.booster` pump II preferably but not necessarily mounted on the bottom wall of the tank, and a screen assembly I2 mounted over the throat opening of the booster pump.

The fuel tank I0 has a vent member I3 provided in the top wall thereof and an outlet opening I4 in its bottom wall within which the booster `pump I I is mounted. 4

.An annular member I la has anenlarged portion Hb adjacentv the inner periphery thereof i inserted into the opening I4 and an annular scattered bubbles An annular outer shoulder I8 on the throat member provides a seat for a pump casing I9 which is connected to the annular member Ida by means of studs Ile. chamber in the pump casing opens along the outer periphery into a 4 which in turn is connected to a fuel delivery line 22.

The pump impeller. comprises a hub V23, a

flange 24 and av series of curved vanes 25. The impeller is'secured to a driving shaft 26 by a key (notvshown) and a nut 21.

-The outer periphery of the impeller, defined by the ends of the vanes'25`,

in order that the fuel be delivered under pressure through the volute 20 into' the delivery line 22. A casing portion 29 houses the driving shaft 26 and is connected to a source of motive n i impeller, such as an electric motor (not shown).

power for driving the As liquid fuel an in me tank news through .the

throat, the revolving'impeller vanes 25 create a whirlpool action in the fuel. The portionsa ofthevanes whichl underlie the throat member I5 effect a radial pumping of the liquid fuel to deliver it under pressure to theoutlet 2l while the vane portions 25D which underlie the throat openingll effect an agitation of the gas-fuel mixture flowing into the throat to beat bubbles out of the liquid. the fuelis funnel-shaped andthe agitated fuel is whirled in a corkscrew path upwardly and outwardlyjfrom the vanes. This constant vbeating of the fuel effects an increased generation of gas and vapor bubbles over that which normally results from decreased atmospheric pressure alone*v l The bubbles as the `aircraft yrises in altitude. are carried outwardly and upwardlybyvthe liquid 'stream flowing in a corkscrew path leaving only fully liquid fuel at the axes'of the throat l to'be ,pumped by the vanes into the outlet.y It isato be noted that the gas bubbles form along the vane portions 25D and traveloutwardly and rupwardly away from'the rotational'axes of the impeller.

When the aircraft is operated at low altitudes,

the fuel 30 is in a substantially fully liquid state and the pump impeller merely delivers the fuel under pressure into the delivery line. However, as the altitude range of the aircraft `is increased, a point is eventually reached inwhich there is a separation of air, other fixed' gases, or vapors from the liquid fuel in the tank.V This condition is aggravated as the altitude is increased. When the fuel in the tank starts breaking up, 3l will appear inthe pond of fuel throughout the tank. Asthe liquid fuel flows through the throat, the revolving impeller vanes 25 create a whirlpool action.' The portions 25a of the vanes, hich underlie the throat, effect a radial pumping ofthe liquid fuel to deliverit under pressure to thefoutlet 2l while lthe vane portions 25h, within the throat opening defined by the annular-inlet l1, effect an agitation of the gas-fuel mixture flowing into An internal volute discharge member i 2l is positioned be-v tween the throat member and an annular flange" y portion 28 on the inside of the pump casing I3 The whirlpooly action withinv screen portionf 32 ldamage the vanes on the rotating impeller.

thereto yby any suitable means,

I line from which it is easily removed and cleaned.

This screen filters fine particles of foreign matter from the fuel. When a booster pump is provided as in the present instance, it is necessary to screen any rigid particles from the fuel before it enters the` pump as such particles would In providing such a screen, it is essential that it be so constructed as not to interfereA with the separation of the gaseous bubbles from the liquid fuel, asl herein .previously described. Such a` screen assembly willV now be described.

The screen or filterassembly generally cylindricalA screen member 32. The screen is preferably 4formed of material which is inert when submerged in fuel such as gasoline. It is also preferred` that, the coarseness of the screen be 8 mesh, although this maybe. varied as desired.

. A ring member 33 is connected to the throat member I5v by means of screws The ring member 33 has an upwardly extending flange 35 at its inner periphery for connection to the marginal' peripheral surface at one end of the screen. Connection therebetween is effected by anyfsuitable meanssuch as solder or the like. .It is tobe noted that the diameter of the is substantially the same as the' diameter at the widest end of the tapered throat surface I6. Thisrelationship will be explained in greater detail hereinafter.

A screeninsert member 36, of the same material-and meshas the screen member 32, is inserted into the upper end thereof Vand connected the `screen vassembly I2' in the form of or the like.- Obviously can be formed of screen material a cup of one-piece` construction.

As -best shown in Figures 1 and 3, 'a vbaille or defiecting member V31 isconnected to the inner periphery of the screenfportion 32 by any suitable means, A such fas' solder. member isvpositioned in spaced relation from the lower .or open end yof the screen andA preferably closer thereto than to the closed'end. The defiecting member 31 is formed preferably of thin sheet `brass having a substantially cylindrical portion 38 for connection to the screen portion 32 and a defiecting portion 33 in angular relation to the cylindrical portion. The defiecting portion 3!) is apertured as at 40 and inthe preferred kform of construction the ,diameter of this aperthe cylindrical A fine mesh I2 comprises a I 3l or the like.v

such as solder This defiecting n the bubbles.

wardly as they rise above the throat. Conse-V quently, it is desirable that the cylindrical portion 32 of the screen assembly be positioned as close to the throat as possible so that the gas bubbles 3| will be forced through the screen p0rtion thereof to travel outwardly in the fuel in the fuel tank before rising upwardly toward the top thereof. This permitsfully liquid fuel to be drawn through the top and` side portions of the screen assembly above the deflector member 31 assembly similar to the assembly I2- is vprovided."`

without drawing the gasbubbles'3l back into the screen.' This flow path of fully liquid fuel is illustrated in Figure 1 by the'solid-line arrows. The fuel isy screened or filtered as it is drawn through the screen assembly I2 andthe fully liquid fuel is drawn axially downward into the booster pump Il where it is delivered to the delivery line 22. ."I'his delivery is, of course, only under pressure greater than atmospheric when the booster pump is in operation. l

As the light gas bubbles 3l riseabove the booster pump throat and the rwhirlpool action forces them outwardly from they screen assembly I2, they strike the deflector and are deiiected through thelower portion ofthe screen portion 32. Consequently, the deflector'ispositioned to deflect the greatest number of the free bubbles as they risey in a curved path. It is obvious that the angularltyof' the defiector portion' 39 may be varied from a position extending radially inward from the side walls of the screen assembly to a position nearly tangential to the curved path of A screen of the type shown in Figure 1 will tend to block the low of bubbles 3l entrained with the liquid fuel passing through the lower screen portion in the 'corkscrew path. Obviously, this blocking action depends onthe fine. ness of the screen, the size of the bubbles and the velocityv of flow of the fuel in the corkscrew` path caused by the agitation of the fuel by the impeller.

An impeller of the type illustrated causesfne bubbles to form along the tapered agitating portions 25b of the vanes. These bubbles and fuel y are induced to iiow outwardly and upwardly from the rotational axes of the impeller byits agitatlng action. As the bubbles collect together and rise upwardly in the fuelftheyincrease in size. It is therefore necessary to position the screen as closely as possible to the throat to permit theA bubbles to escape therethrough before growing to a size where they would be blocked by the screen mesh.

While the greater number of bubbles are thrown outwardly beyond the screen and rise to the surface of the fuel pond, many are pulled baci-:toward the top of the screeninthe path of fuel fiowing toward the impeller. However, since the bubbles, when they reach the top -portion of the screen, have grown in size and the velocity of fuel fiow is low because of the large screen area through which the fuel enters, they will be'trapped on the screen from where they rise to the surface of the fuel pond and escape.

It will be apparent from the foregoing description that the screen portion below the defiector member 31 must be sufficiently coarse to permit gaseous bubbles to iiow therethrough in the stream of liquid fuel owing in the corkscrew path generated by the impeller. Furthermore, it isv highly desirable that the screen portion above the deflector 31 be sufficiently fine as to trap on the outside thereof the greater number of gaseous bubbles following the relatively slow stream of liquid fuel flowing into. the screen to be drawn through the impeller and ejected un?y modified screen assembly as illustrated in Figure 4.

In this modified form of construction, ascreen The lower portion 50 is preferably of 8 mesh screen or coarser and is vpositioned above the throatlS and connected thereto. by a ring mem-L ber 33 and screws 34 vin the same manner as shown in Figure 1. The deflecting member 31 has the lower portion only of its cylindrical por` tion 38 connected to the inner periphery of the screen portion 50 by means.

The upper portion 5| of the'screen, instead of being formed of screen Amaterial of 8 mesh, is formed of a mesh material of suliicient neness to screenne foreign material from the' liquid fuel owing as indicated by the solid-line arrows of Figure 1.

' Consequently, thedeflector portion v3&1 aids in defiecting gaseous bubbles through a coarse* screen therebelow while the substantially'gasfree liquid fuel flows through va fine screen above the deflectorY into an axial path where it downwardly into the booster pump. Y

lSuch a screen assembly could replace the usual filtering screen in the delivery. line or, if it does not replace the usual filtering screen, it will aug--v ment filtering of the fuel before it reaches the engine carburetor.

It will 'be apparent from the foregoing that I have provided'a filtering assemblyfor a gas and liquid separating device for use in a fuel system for aircraft. Furthermore, the arrangement of this invention providesa filteringassembly which defines fiow paths for fully liquefied fuel and bubbles which rise in theA for the separated gas fuel in the tank. l

While a particular embodimett only of this invention has been 'illustrated ity will, of course, be understood .that the invention should not be limited thereto, since many modifications may be made and, therefore, it is contemplated by the appended claims tol cover all such modifications as fall within the true spirit and scope of the present invention.

I claim as my invention:

1. In a gas and liquid separating device including a throat receiving gas and liquid from a pond, and an impeller effecting circulation of liquid in the pond and separation of gas bubbles from the 1iquid the improvement comprising a filter in said pond surrounding said throat to strain liquid flowing to the throat, and mea'ir in said filter spaced from the throat to deflect gas bubbles from the impeller through the filter.

2. In a gas and liquid separating device lin'- cluding a throat receivinggas andliquid'from a pond, and an impeller effecting circulation of liquid in the pond and separation of gas bubbles from the liquid, the improvement comprising a filter inA said pond surroundingsaid'throa'tto strain' liquid owing'to theA throat, and a defiector in said filter spaced from the throat subst'antially defining separate paths vfor liquid int'owsaid throat and for gas bubbles away from said throat and through said filter.

3. In a gas and liquid separating device` in' cluding a throat receiving gas and llquid froma pond, and an impeller effecting circulation of liquid in the pond and separation of gas bubsolder or other suitable is drawnl filter and having an Y said deflector opening denlng a downward path for liquid into said throat and from the impeller in spaced relation bles yfrom the liquid, the improvement com; prising ay meshed iilter in said pond surrounding tured deilector portion extending inwardly and at an angle of substantially 60 from the side walls and extending upwardly away from' said throat to strainliquid flowing to said throat, and an apertured deilector member e. tending angularlyr sidewalls of said filter, said de inward from the downward path for liquid now through the-apertured portion thereof and a delf fleeting surface l away from said path.

cluding a throat receiving gas and liquid from a pond, and an impeller effecting circulation of liquid in the pond and separation of fromthe liquid, the improvementcomprlsing a o from said throat to strain liquid flowing to rsaitlthroat, a frusto-conical sheet metal deilector member extending in-y wardly from the 'side ywalls of said filter at an angle of substantiallyv60 therefrom, said denector defining therethrough a path for liquid into said-throat the gas bubbles rising from wardly through the filter.

5. In a gas and liquid separating device including a tapered throat receiving gas and liquid from a pond, and an impellcr effecting circulation of liquid in the pond and separation of gas bubbles from the liquid, the improvement comprising a cylindrical meshed meshed closure walilat one end thereof, said filter closely surrounding the widest end of said tapered throat `to strain liquid flowing into the throat, a sheet metal deector memberextending angularly inward from the side walls of `said axial opening therethrough,

tending upwardly away while deflecting said angularly extending portion defiecting gas bubbles rising a path outwardly through said filter. Y Y

6. A filter assembly for` fluids comprising a cup-shaped meshed member, deilector member extending inwardly from the inner periphery of said cup-,shaped member in v from the open end thereof.

7. A filter assembly for fluids comprising a cylindrical meshed member, a meshed closure member at one and an apertured sheet metal deector member extending inwardly from the inner periphery of said cylindrical member in spaced relation from the other end thereof.

8. A nlter assembly for fluids comprising a cylindrical meshed member, supporting means for said cylinder ymember at one end thereof, a meshed closure member at the other end thereof, and an axially apertured `sheet metal deflector memberA extending inwardly and at an acute anglefrom the side wallsof said cylindrical member adjacent the supportedV end thereof.

9. A filter assembly for fluids comprising' a cylindrical meshed member, supporting means for said cylindrical member at one end-thereof, a flanged meshed closuremember in the other end ofs'aid cylindrical member, and a deflector member in said'cylindrical member in spaced relation from the'supported end thereof, said deflector'member being closer to said supported end than to said other end of the cylindrical member, s aid deflector member having a cylindrical portion connected to the inner periphery of saidcylindrical for diverting the gas bubbleslm 4. In ay gas and liquid separating device in-ldownward axial the in'ipeller outand a sheet metal' end of .said cylindrical member,

gas bubbles I meshed filter in said pond surrounding and exfiltery having f a member-and an axially apery the pathof liquid the'inletof a pump .fine a localized inlet flow path 1l. In a booster pump including an inlet throat' material from a pond and an pumping vane porreceivuig uquia n impeller assembly having a tion and an agitating ram portion for beating 1 bubbles of gasandrvapor out of the liquid to' travel upwardly in the pond along aI path diverging from the axis of the throat, the improvement ofa. strainer in y throat and yhaving a c'oarse mesh -portion' in the path of the bubbles anda finer mesh portion in flowing to the throat.

12; A lter assemblyr adapted for disposal over the vinlet of a pump beating out bubbles of gasand vapor from liquid passing through the filter and pumping means '.for pressuring Y comprises an annular meshed'memberladapted, Yto be positioned adjacent the inlet yof 'such a pump, and a cup shaped meshed member form the bubble freed liquid, which ing an` extension of said annular member for extending away from the inlet of such a pump,

the mesh of said annularmember being of great-1 er coarseness thanv the ymesirof said cup shaped member whereby liquid flowing to the pump ,is adapted to. be filtered through the cup-shaped member and whereby bubbles freed from the pump arfeadapted to pass through the annulark r'member..

13. A filter assembly adapted for disposal over having agitating means for beating out bubbles of gas and vapor from liquids passing `through the filter and pumping means for pressuring' the bubble freed liquids which comprises'an annular meshed member adapted to be positioned adjacent the inlet of such a pump,

a cup shaped meshed member forming an extension of saidla'nnular member and adapted to' extend laway* from the inlet of such a pump,

the mesh of said annular member being of greater4 coarseness than the mesh of said cup-shaped member, and an apertured deflector member be-vr tween the annular meshed member and the cupshaped meshedimember extending inwardly from the filter assembly at an angle to the annular memberwhereby sairLassembly is adapted to be submergedv intliquid land bubbles liberated by!4 such a pump are adapted to flow through the annular memberuandrise in the liquid while being prevented from re-entering the filter by the cup-shaped member.

14. InV apump device for beating out bubbles of gas and vapor, from a liquid flowing thereto andY for pressuring the bubble-freed liquid, the f `improvement of guide shield adapted to be mounted inthe ,liquid a relatively shallow annular from said pump device to `deto the device and to cooperatey withr the pump devicey to define therebetween a flow path for the gas and vapor bubbles in the liquid.

in spaced relation` RUSSELL a. CURTIS.

fluid inlet throat `the pond spanning the having agitating means for' 

